It is known to mix liquid esters and aqueous basic solutions of phenolic resins with sand to make foundry mixes which are made into foundry shapes by the no-bake process. Although these binders have some advantages from an environmental standpoint, the physical properties of the foundry shapes made with these binders are generally inferior to those made from polyurethane-forming binders. In particular, the tensile strengths of foundry shapes made with the liquid esters and aqueous basic solutions of phenolic resole resins are lower. Consequently, there is an interest in finding additives or otherwise modifying the formulations of these binders to improve the tensile strengths of the foundry shapes made with these binders.